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Scientists compile list of all known Amazon tree species, say it could take three centuries to find the rest

  • After sifting through more than half a million museum specimens collected in the Amazon between the years 1707 and 2015 (530,025 specimens, to be precise), the researchers were left with a list of 11,676 known tree species in 1,225 genera and 140 families.
  • Nigel Pitman, the Senior Conservation Ecologist at Chicago’s Field Museum and a member of the team, said in a statement that that number — 11,676 known species — suggests the 2013 estimate of 16,000 total species is most likely accurate, which would leave about 4,000 of the rarest Amazonian trees still to be discovered and described to science.
  • The scientists hope that the checklist they’ve compiled of Amazonian tree species will become a valuable resource for ecologists studying the rainforest.

Back in 2013, an international team of botanists estimated that there were about 16,000 species of trees in the Amazon rainforest.

No one had ever actually counted up all of the species we already know about, however, so many of those same scientists, led by Hans ter Steege at the Naturalis Biodiversity Center in the Netherlands, went ahead and did so earlier this year. The results show that, as it turns out, the original estimate of 16,000 was pretty much spot on.

The team delved into museum collections from around the world to determine how many tree species have been recorded in the Amazon so far, and to try and ascertain how many species there might be out there that have yet to be discovered. They published their findings yesterday in the journal Scientific Reports.

After sifting through more than half a million museum specimens collected in the Amazon between the years 1707 and 2015 (530,025 specimens, to be precise), the researchers were left with a list of 11,676 known tree species in 1,225 genera and 140 families.

The study relied on digitized botanical collections from museums, as shown here at The Field Museum in Chicago. Photo by Kevin Havener/The Field Museum.

Nigel Pitman, the Senior Conservation Ecologist at Chicago’s Field Museum and a member of the team, said in a statement that that number — 11,676 known species — suggests the 2013 estimate of 16,000 total species is most likely accurate, which would leave about 4,000 of the rarest Amazonian trees still to be discovered and described to science.

“Since 1900, between fifty and two hundred new trees have been discovered in the Amazon every year,” Pitman noted. “Our analysis suggests that we won’t be done discovering new tree species there for three more centuries.”

The scientists hope that the checklist they’ve compiled of Amazonian tree species will become a valuable resource for ecologists studying the rainforest. “We’re trying to give people tools so they’re not just laboring in the dark,” Hans ter Steege said in a statement. “The checklist gives scientists a better sense of what’s actually growing in the Amazon Basin, and that helps conservation efforts.”

To complete their study, the team relied on the digital records of the specimens housed in museum collections that are shared worldwide through aggregator sites like IDigBio. “We couldn’t have written this paper without digitization efforts,” Pitman said. “All of the information we needed was in the same place, so we didn’t have to go through every individual museum in the world.”

Of course, digital records won’t help in discovering all of the unknown species that are still out there. “Finding, describing, and documenting the distribution of the remaining species will require coordinated efforts at under-collected sites,” the team notes in the study.

Amazonian forest in the Putumayo Basin of Loreto, Peru, was surveyed during a February 2016 rapid inventory by The Field Museum. Photo by Nigel Pitman/The Field Museum.

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